Skidmore et al. have proposed a concept for an array of self-assembling micro-manipulators. They show exponential assembly through the sequential fan-out of manipulators assembling other manipulators and show that in N steps the system can assemble 2N manipulators. [G. D. Skidmore, E. Parker, M. Ellis, N. Sarkar, and R. Merkle, “Exponential assembly,” Nanotechnology, vol. 12, no. 3, pp. 316-321, September 2001.] This concept, however, requires pre-fabricated sheets of component parts and is not capable of making arbitrary structures. Pelrine et al. have demonstrated a system in which many robots controlled in parallel can work together to build structures. The system is comprised of a substrate with carefully routed electrical traces and permanent magnet “robots” which levitate above the substrate and are controlled by a central processor. [R. Pelrine, A. Wong-foy, B. Mccoy, D. Holeman, R. Mahoney, G. Myers, J. Herson, and T. Low, “SRI Robot Swarm,” 2012.] A NASA Institute for Advanced Concepts report details some concepts and guidelines for the design and development of self-replicating systems. [T. Toth-Fejel, “Modeling Kinematic Cellular Automata Final Report,” pp. 1-74, 2004]. Of these, the Moses Universal Constructor [M. Moses, “A Physical Prototype of a Self-replicating Universal Constructor, University of New Mexico, 2001] has come closest to physically realizing a self-assembling system but was limited because the feedstock was overly complex and did not allow for the construction of strong, scalable systems.
This invention describes a robotic assembler, a “robosome,” that can assemble almost anything, including itself.
The complexity and diversity of life is based on an inventory of just twenty parts, the common amino acids, which are combined by the ribosome to create the range of molecular machinery. Their discrete construction allows errors to be detected and corrected, global geometry to be determined by local constraints, and the scalability of ribosomes making ribosomes. This invention brings these attributes into regimes of engineered materials that are not available in molecular biology.
This invention is accomplished by developing a basis set of building blocks that are inorganic analogs to amino acids. Instead of basic vs. acidic, hydrophobic vs. hydrophilic, . . . , these are conducting vs. insulating, ferromagnetic vs. ferroelectric, . . . . They are linked by mechanically reversible joints analogous to bonds, with a workflow to design with them and plan their placement. The assembler is initially conventionally constructed, and then in stages its components will be replaced with the parts that it's assembling. The assembler is essential to this roadmap, and is itself a paradigmatic test case for the integration of a functional system.
The outcome of the invention is digitized fabrication, analogous to the earlier digitization of communication and computation, by embodying codes in the construction of materials. Beyond the current focus in advanced manufacturing on additive versus subtractive processes, this invention introduces a much more fundamental transition to assembly and disassembly. Potential disruptive benefits include a radical simplification of material supply chains down to a small number of feedstocks, and the ability to exponentially ring up manufacturing capacity on demand.
Benefits of building functional systems with assemblers that assemble assemblers include:                Saving time: the time for a product to go from component vendors, to OEMs, to inventory, to delivery can be replaced by production in the field.        Simplifying supply: large inventories and long supply chains to remote locations can be replaced by assemblers fed by a standard set of parts.        Rapid customization: because assembly is done on demand, what is produced can be dynamically modified to match a mission.        Increasing integration: technology today is poorly integrated across length scales; by spanning them with a common process, size and weight can be reduced, and related capabilities combined.        Eliminating waste: unneeded products can be disassembled to their constituent components and reused, rather than disposed.        Adding capacity: because assemblers can be tasked to build other assemblers, manufacturing capacity can be increased exponentially rather than linearly to meet demand.        Adapting designs: by retaining assemblers as part of the systems that they assemble, they can become reconfigurable to adapt to dynamically changing requirements. Alternative approaches include:        3D printing: This is currently receiving a great deal of attention, but is limited in the range of properties compatible with a multimaterial printing process. Expensive inks are needed for good conductors, and semiconductors show poor carrier mobility. The approach taken here can instead assemble elements made from bulk electronic materials.        IC fabrication: Chip fabrication requires millions of dollars for mask sets, billions of dollars for fabs, and turn times of many months. The approach taken here does not aim to compete with the incremental cost per chip following that investment of time and money; it targets significantly reducing both the time and cost for quickturn, lowrate production. Existing chip fab is also limited to on the order of ten metal layers; the assembly approach aims to significantly increase complexity with a fundamentally three-dimensional process.        Electronics manufacturing: The pick-and-place machines used to assemble circuit boards are two-dimensional and analog parts can be placed in arbitrary locations on boards. The task of the three-dimensional assembler to be developed is simplified by the discretization of the material, quantizing the motion system to relative displacements on a lattice. Also, part feeding is simplified from large numbers of varying reels to small numbers of standard shapes.        Reconfigurable robotics: This promises universal rather than special purpose robots, but the smallest pitches have been on the order of a centimeter, and the number of modules in the range of tens to hundreds, limited by the demanding system integration required. The assembler to be developed is a new kind of reconfigurable robot, building modules out of, rather than into, the primitive elements.        Materials genome: These initiatives have been something of a misnomer, because they are more like recipes, cataloging how a wide range of materials can be continuously combined to vary their properties. The approach to be taken here is much more like a genome, with a small set of basis components.        Self-assembly: the complexity that can be attained with self-assembly is limited by diffusional time scales, error accumulation, and an exponential difficulty in coordination. Biological assembly, like this invention, is better understood as coded rather than self-assembly, with messenger RNAs bringing instructions, transfer RNAs bringing parts, joints being made in the ribosome, and chaperones guiding folding.        
This invention mandates revisiting decades of assumptions and historical practices about the nature of design representations, material specifications, manufacturing process planning, and machine and motion control. The “robosome” assemblers are a new kind of relative robot, that functions as a part of the structure that it's assembling. This process will be reversible, replacing disposal with disassembly and reuse.
The most profound question posed by this invention is what the minimum requirements are to bootstrap a technological civilization. Models for in-situ resource utilization typically recapitulate the stages of the industrial revolution; this invention can instead be thought of as the technological equivalent of the evolution of the building blocks for life. The results will be particularly relevant for operations in remote, resource constrained, and rapidly changing environments that cannot assume existing support infrastructure.